1. Field of the Invention
This invention relates to circuit breakers of the type described in United States Patent No. 3,114,023, issued Dec. 10, 1963 to R. E. Locher. In particular, this invention relates to an electric arc cooling and quenching means for use in such breakers, such as a combination of a pair of composition sheets and a channel for providing electric arc cooling and quenching therefor. Accordingly, it is a general object of this invention to provide new and improved cooling and quenching means of such character.
2. Description of the Prior Art
Circuit breakers of the type described in the foregoing patent are often referred to as minimum modulus because the pole width is a minimum for circuit breakers of the same and higher electrical ratings and which have the same or similar profile configuration. The minimum modulus circuit breaker is typically designed to be used in the same panel board as circuit breakers of twice the width, similar profile and same ratings. The circuit breaker described by Locher is distinct in that the ratio of its width to its height and breadth is low relative to circuit breakers of the same electrical ratings.
The existence of composition sheets in an electrical circuit breaker for providing electric arc cooling and quenching therefor is known. Also, the existence of a channel in an electrical circuit breaker for providing electric arc cooling and quenching therefor is known. However, the combination of the composition sheets, together with a channel, which combination yields synergistic results in an electrical circuit breaker, was not heretofore known.
3. Statement in Accordance with 37 CFR 1.56
In accordance with the provisions of 37 CFR 1.56, the following patented art may be of interest.
______________________________________ U.S. Pat. No. Patentee ______________________________________ 2,428,254 Walle 2,654,815 Laverty 2,768,264 Jones et al. 2,830,158 Coleman 3,043,938 Daly 3,327,080 Meinders 4,217,472 Gryctko et al. ______________________________________
Walle, U.S. Pat. No. 2,428,254 discloses a circuit breaker having an arc chute covered with a layer of electrically insulating heat refractory material. With regard to various modifications of circuit breakers depicted in FIGS. 1-6 thereof (FIG. 7 is applied to an insulating support), no electrically conductive runner for the arc is provided.
Laverty, U.S. Pat. No. 2,654,815 discloses an electric circuit interrupter with various forms of housing. One form of housing, depicted in FIGS. 1 and 2, is constructed of metal, and forms an arc chamber which surrounds or encloses contacts as closely as is mechanically feasible. Another form, depicted in FIGS. 3 and 4, is a contact housing, or arc chamber, which, with the exception of one end wall, is made up of sheets of fibre; no end wall opposite end wall 22' is provided. Yet another form, depicted in FIGS. 5-8, includes a housing with side walls provided with inner fibre linings with extension of a lining through the top wall, so that there are fibre pieces adjacent the side edges of the contacts. Still another form, depicted in FIGS. 9-11, includes an arrangement of a metallic strip having a central portion forming an end wall and portions extending at right angles thereto to form top and bottom portions, together with a pair of fibre side plates.
Jones et al., U.S. Pat. No. 2,768,264, states that it is objects of their invention to provide an arc-suppressing shield having improved arc-suppressing characteristics, and to produce a molding composition which can be employed to mold switch-enclosures, fuse enclosures, or the like having improved arc-suppressing qualities. Jones et al. discloses compositions for suppressing arcs; the subject matter of said patent is incorporated herein by reference.
Coleman, U.S. Pat. No. 2,830,158, discloses a circuit breaker including a fixed contact disposed in a chamber formed within a recess of a base. A mechanism is provided for actuating a pivotal contact arm cooperating with the fixed contact. An atmospherically insulated sealed lining forms arc extinction means for the chamber, the lining retaining pressurized gases therein to suppress the arc, and isolating such gases from erosive contact with the actuating mechanism during all positions of the pivotal arm.
Daly, U.S. Pat. No. 3.043,938 relates to means for suppressing arcs incident to the separation of contacts in an electric switch. Plates are stamped from fiber insulating sheet material which have the property of powdering away under the heat of an electric arc and also of tending to suppress the arc more quickly. "This property has been well known for many years and need not be further explained".
Meinders, U.S. Pat. No. 3,327,080 discloses an arc chute which is provided with means for cooling the exhaust gases expelled from the top of the stack of plates. Such means take the form of hollow baffle members which are supported by perforated insulating members.
Gryctko et al., U.S. Pat. No. 4,217,472, discloses a circuit breaker having an arc chute. The arc chute includes a plurality of metal arc plates held in closely spaced face-to-face relationship by staked side protrusions which are received by positionning apertures in relatively rigid insulating side members. A cap constructed of folded insulating sheet material closes the rear of the arc chute and extends forward adjacent a portion of the main planar section of the last arc plate.